Generally, a gas insulated switch is located inside a substation between a 3-phase high voltage and an overhead transmission bus. If an abnormal voltage such as lightning or a surge voltage is detected, the gas insulated switch serves to block a current.
The gas insulated switch includes a bushing that is applied with a power from a 3-phase high-voltage power source, a gas insulated bus that transfers the power applied to the bushing to a gas insulated breaker, and a gas insulated breaker that blocks the power applied from the gas insulated bus.
As illustrated in FIG. 6, the gas insulated bus includes a tank 70 filled with an inert gas, conductors 71 provided with a predetermined interval being maintained inside the tank 70, and insulation spacers 72 arranged transverse to the longitudinal direction of the conductors 71 and supporting the conductors 71. The conductors 71 having three phases are provided inside the tank 70.
The insulation spacer 72 includes an insulator 721 and a connection conductor 722 coupled to the end surface of the insulator 721 and the end surface of the conductor 71 along the longitudinal direction of the conductor 71, and in order to maintain the facing contact, the conductor 71 is assembled to the connection conductor 722 by using bolts 73. The end side of the conductor 71 is coupled to attachment members 74 by welding. The attachment member 74 formed by molding has an attachment groove 741 where the bolt 73 is attached. Electric field is highly likely to be concentrated on the attachment groove and corners of the attachment groove. Therefore, dielectric breakdown may occur, and thus, there is a problem in that bus-to-ground short circuit occurs.
The attachment grooves of the attachment members small and are formed in several directions, so that there is a problem in that it is difficult to attach the bolt in the process of assembling. Therefore, there are problems in that the assembling and dissembling operations are difficult, and work time becomes long.
In addition, there is a problem in that the insulation distance between the bus and the ground is increased, and the size of the bus is increased.